JP4499446B2 - Ball mounting apparatus and ball mounting method - Google Patents

Description

  The present invention relates to a ball mounting apparatus provided with a cleaning unit for cleaning a transfer pin, and a ball mounting method including a cleaning step of removing flux adhered to the transfer pin.

  2. Description of the Related Art Conventionally, as a transfer pin cleaning device that constitutes a ball mounting device, a device that adsorbs a flux adhering to a transfer pin to a flux adsorbing material (for example, non-woven fabric, paper) is commonly used.

However, the conventional cleaning device has a problem that the state (normal or abnormal) of the transfer pin cannot be visually observed. Furthermore, there is a problem that the transfer pin is easily deformed and flux remains.
JP 2001-7136 A

The problem to be solved is that it is impossible to inspect whether or not the transfer pin is normally set in the fluxk cleaning device provided in the ball mounting device.
Another problem is that the transfer pin is easily deformed and flux is likely to remain on the transfer pin.

  The ball mounting device of the present invention is a pin transfer type ball mounting device having a cleaning device, and the cleaning unit transfers the flux attached to the transfer pin in order to remove the flux attached to the transfer pin. And a heating device for heating the cleaning surface.

  The ball mounting apparatus of the present invention is characterized in that the cleaning surface is heated to 30 to 40 ° C. by a heating device.

  The ball mounting method of the present invention is characterized by having a step of heating the flux.

  The ball mounting apparatus and the ball mounting method of the present invention have an advantage that it is possible to inspect whether the transfer pin is normally set by the flux cleaning unit by visual inspection or image processing technology.

  The ball mounting apparatus and the ball mounting method of the present invention have an advantage that the transfer pin is not deformed and flux does not remain on the transfer pin.

  The ball mounting device and the ball mounting method of the present invention have the advantage of being able to adjust the viscosity and surface tension of the flux, in addition to the effects of the ball mounting device.

A ball mounting apparatus and a ball mounting method equipped with a cleaning unit that can visually determine whether or not the transfer pin is in a normal state by visually observing the transferred flux and that does not deform the transfer pin and does not leave the flux on the transfer pin. It was realized.

  FIG. 1 is a plan view of a ball mounting apparatus according to the present invention, in which components are shown as blocks.

The loader 1 is provided with a magazine for setting the substrate 15. The substrate 15 is sent from the magazine along the substrate guide 11 to the flux transfer position, the ball mounting position, the ball mounting inspection position, and the unloader 9 as necessary, and further to the reflow furnace. The substrate 15 sent to the flux transfer position and the ball mounting position is indicated by reference numerals 15a and 15b.

The transfer device includes a transfer head 2, a transfer unit 3, and a cleaning unit 4. The transfer head 2 can be freely moved in the Y-axis direction by a Y-axis slider, and can be rotated and moved up and down by being connected to a θ-direction drive device and a Z-axis drive device. The transfer head 2 is in a standby position, and can be arbitrarily moved on the transfer unit 3, the substrate 15a, and the cleaning unit 4 from this position. The CCD camera 16 is used for observing the flux transferred to the cleaning surface and aligning the substrate 15a and the transfer head 2. The observation and alignment of the flux are different operations, and a different camera may be used. When the transfer state of the flux is monitored only by visual observation, the camera for monitoring the flux may not be provided.

The mounting device includes a ball suction head 5, a ball supply unit 6, and a lighting device 7 for ball suction inspection. The ball suction head 5 can be freely moved in the plane by the X-axis slider 13 and the Y-axis slider 12, and is further connected to the θ-direction drive device and the Z-axis drive device to rotate and move up and down. It can be done. The ball supply unit 6 includes a vibration device, a parts feeder 19, a ball vibration container 20, and a ball amount detection sensor 21. Details of the mounting device have substantially the same structure as that of JP-A-2002-299808.

The ball mounting inspection device 8 is a device that inspects whether or not the ball is normally mounted on the substrate by capturing the image of the state where the ball is mounted on the substrate with a CCD camera and processing the image. The ball mounting inspection device 8 can be moved to the standby position by the slider 18 because it becomes an obstacle during the repair process.

The repair unit 10 is a device that repairs a mounting failure of a ball. When the ball mounting inspection device 8 determines that no ball is mounted on the land of the substrate 15b, the head of the repair unit 10 adsorbs the ball and moves onto the land where the ball is not mounted to mount the ball. . When it is determined that an extra ball is mounted, a mechanism for removing the ball with a head provided in the repair unit 10 can be added.

FIG. 2 is a front sectional view of the transfer head 2, and FIG. 3 is a sectional view taken along AA in FIG. The transfer head 2 includes a pin unit 22, a pin guide plate 23, and a fixing member 24. The pin unit 22 includes a transfer pin 25, a pin holding plate 26, a pin unit fixing plate 27 and a spring 28. In the pin unit 22, six sets other than the leftmost set are illustrated by only the transfer pin 25.

The transfer pin 25 is made of stainless steel (SUS303) and plated with gold. The transfer pin 25 has a root portion that is thicker than the middle portion and the tip portion, and a tip portion that is an arc. The guide hole provided in the pin guide plate 23 is smaller than the base portion of the transfer pin. The transfer pin 25 is guided by the guide hole and can move up and down, but is not dropped by the pin guide plate 23. The pin holding plate 26 functions so as not to be detached from the pin guide plate 23 when the transfer pin 25 is guided by the guide hole and moves up and down.

The spring 28 is disposed between the pin holding plate 26 and the pin unit fixing plate 27 and urges the pin holding plate 26 to which the transfer pin 25 is attached downward. Due to the biasing force of the spring 28, the transfer pin 25 pressed downward moves upward with a relatively small force, so that a large stress does not act on the transfer pin 25 during the application and transfer of the flux. The deformation of the pin 25 is prevented. Although it is preferable that the tip positions of the transfer pins 25 are all equal, variations occur due to component dimensional errors, mounting errors, etc., and some of the defects caused by these variations are corrected by the spring 28.

Air holes (29, 30) are provided in the fixing member 24 and the pin unit fixing plate 27. The compressed air is sent through this air hole. This compressed air acts on each of the transfer pins 25 and always presses the transfer pins 25 downward. Thereby, the tips of the transfer pins 25 can be aligned. Note that a drain hole is provided on the side surface of the transfer head 2 so that the compressed air is constantly removed. In the transfer head 2, the tips of the transfer pins 25 are aligned by a double method of a spring 28 and compressed air.

4 is a plan view of the transfer unit 3, and FIG. 5 is a cross-sectional view taken along line AA in FIG. The transfer unit 3 includes a squeegee 17, a flux table 32, a squeegee guide 31, and a slider 14.

The squeegee 17 is composed of two squeegees with blades for leveling the flux at the tip thereof, and has a structure that can move up and down independently. The squeegee guide 31 is provided with a drive device 35 that moves the squeegee (17a, 17b) up and down. The flux 33 is supplied between the squeegees (17a, 17b). When the flux 33 is moved in the left direction, the squeegee 17a is used, and when the flux is moved in the right direction, the squeegee 17b is used. The squeegee guide 31 is connected to a motor via a ball screw 36 and a connecting member 34, and can move left and right by the rotation of the motor.

The flux table 32 is provided with barriers 37 at both ends, so that the flux 33 does not escape from the flux table 32. The flux 33 is leveled by the squeegee 17 and formed to have a constant thickness.

6 is a plan view of the cleaning unit 4, and FIG. 7 is a cross-sectional view taken along the line AA in FIG. The cleaning unit 4 includes a cleaning table 38, a heater 39, and a heat insulating material 41.

The cleaning table 38 is made of stainless steel (SUS303). The upper surface is a ground surface that has been surface-ground by the cleaning surface 40. The heater 39 is set in a hole processed in the cleaning table 38. Six heaters 39 are provided with temperature sensors in the vicinity thereof, and the temperature of each heater is controlled independently. If high-precision temperature control is not required, the number of temperature sensors may be one, or the number of heaters 39 may be reduced to 2-4.

A heat insulating material 41 made of porous ceramic is disposed below the heater 39 so that heat from the heater 39 is not transmitted downward.

FIG. 8 is a plan view of the substrate 15. The substrate 15 is a multilayer wiring substrate having via holes, and is composed of 4 × 7 chip substrates 42. A semiconductor chip is mounted on the back surface of each chip substrate 42. The land 44 is omitted from the illustration.

FIG. 9 shows the chip substrate 42 cut by a dicing saw along the cutting line 43. The land on which the flux is transferred and then the ball is mounted is indicated by reference numeral 44.

FIG. 10 is a diagram schematically showing one process of the repair operation, and shows a state in which one ball is supplied to the substrate 15 in which one ball is insufficiently mounted. A land 44 is provided on the substrate 15, and a flux 33 is transferred onto the land 44. Balls 45 are temporarily fixed onto the land 44 with the flux 33 except for one land. On the other hand, a suction hole 47 is opened in the center of the repair head 46, and the ball 45 is sucked into the suction hole 47. The ball 45 is mounted on the land where the ball is insufficient.

Although the transfer state of the flux and the mounting state of the ball are shown in FIG. 10 in an ideal state, in reality, the flux often spills from the land and covers the land. When the substrate 15 on which the solder balls 45 are placed is reflowed, the solder melts and covers the lands.

  A ball mounting method including the step of heating and cleaning the flux adhered to the transfer pin 25 using the ball mounting apparatus of the present invention will be described.

  FIG. 11 is a flowchart of the ball mounting method. In step 1 (S1), the substrate 15 is moved to the flux transfer position and fixed by a clamper. The step of leveling the flux 33 with the squeegee 17 is step 2 (S2).

In step 2, the squeegee 17a is moved to the left to level out the flux 33 and flatten the surface of the flux 33. When the squeegee 17b is waiting at the left end of the flux table 32, the squeegee 17b is moved rightward to level the flux 33. Since step 1 and step 2 are independent operations, any of them may be performed first.

Step 3 (S3) is a step of attaching the flux to the transfer pin 25. The transfer head 2 is moved onto the flux table 32, the transfer pin 25 is lowered into the flux 33, and the flux 33 is attached to the tip of the transfer pin 25. In order to make the adhesion amount of the flux 33 constant, the transfer pin 25 is lowered until the tip of the transfer pin 25 reaches the bottom surface of the flux table 32. Since the transfer pin 25 is biased downward by a weak spring 28, the pin holding plate 26 is pushed up together with the transfer pin 25 when the tip of the transfer pin 25 comes into contact with the bottom surface of the flux table 32.

Step 4 (S4) is a step of transferring the flux 33 adhered to the transfer pin 25 onto the land 44 of the substrate 15. The transfer pin 25 is pulled up from the flux 33 and moved onto the substrate 15 a fixed on the substrate guide 11. Next, alignment is performed using the position mark on the substrate 15 a and the position mark of the transfer head 2. Thereafter, the transfer head 2 is lowered until the transfer pin 25 is attached to the substrate 15a, held for a predetermined time, and then raised.

Step 5 (S5) is a step of cleaning the flux 33 remaining on the transfer pin 25 and adhering thereto. First, the cleaning surface 40 is heated to 35 ° C. by the heater 39 of the cleaning unit 4. The transfer head 2 is moved onto the cleaning surface 40, the transfer pin 25 is lowered until it reaches the cleaning surface 40, held for 0.2 seconds, and then raised. The preferred temperature varies depending on the type of flux. In the present embodiment, a range of 30 to 40 ° C. is preferable. If the remaining flux is small, this step is performed every several times. A preferable holding time is 0.05 to 1 second, and a more preferable holding time is 0.1 to 0.5 second.

Step 6 (S6) is a step of moving the substrate 15a, onto which the flux 33 has been transferred, to the ball mounting position and fixing it with a clamper.

Step 7 (S7) is a ball suction step for causing the ball suction head 5 to suck the ball. The ball suction head 5 is moved onto the ball vibrating container 20. The ball vibrating container 20 is vibrated by a vibration device, and the ball in the ball vibrating container 20 jumps 1 to 2 cm and floats. The pressure inside the ball suction head 5 is reduced, and the floating ball is sucked into a suction hole provided on the lower surface of the ball suction head 5.

Step 8 (S8) is a step of mounting the ball on the land 44 of the substrate 15a. After the ball mounting head 5 that has sucked the ball is moved to the ball mounting position, the ball suction head 5 and the base 15 are aligned. Thereafter, the ball suction head 5 is lowered until the tip of the ball sucked in the suction hole enters the flux transferred onto the land. After the descent, the vacuum of the ball suction head 5 is broken, the ball suction head 5 is raised a little, the ball suction head 5 is vibrated, the flux adhesive force is also measured, and the ball is detached from the suction hole. Then, the ball suction head 5 rises and returns to the standby position shown in FIG.

Step 9 (S9) is a step of sending the substrate 15b on which the ball is mounted to the next step.

Since the transfer head 2 has a structure in which seven sets of pin units 22 are arranged in one row, when transferring the flux 33 to the substrate 15, the transfer operation is repeated four times. When the pin units 22 are 4 rows × 7 sets, the transfer operation is performed once.

FIG. 12 is a flowchart showing a process of inspecting whether there is a concave in the transfer pin or whether there is a bent one using the ball mounting apparatus of the present invention.

Step 11 (S 11) is a step of heating the cleaning surface 40 of the cleaning unit 4, that is, the flux transfer surface, to 35 ° C. by the heater 39. The cleaning surface 40 is a surface subjected to surface grinding so that the transfer state of the flux can be inspected.

Step 12 (S12) is a step of leveling the flux 33 with the squeegee 17 in the transfer unit 3.

Step 13 (S13) is a step of moving the transfer head 2 onto the flux table 32, lowering it, attaching the flux 33 to the transfer pin 25, and then raising it.

Step 14 (S14) is a step of moving the transfer head 2 onto the cleaning surface 40 and bringing the transfer pin 25 into contact with the cleaning surface 40. The flux adhering to the transfer pin 25 is transferred to the cleaning surface 40.

In step 15 (S15), the shape of the flux transferred to the cleaning surface 40 is measured visually or with a CCD camera.

Step 16 (S16) is a step of determining whether the transfer pin 25 is normal or abnormal from the shape of the flux transferred to the cleaning surface 40. The number of transfer pins 25 shown in FIG. 2 is 17 × 17 × 7, which is 2,023. Among these, when the transferred flux has a small shape or the transferred flux is misaligned, it is determined that the transfer pin 25 is defective.

  In the fourth embodiment, when the ball diameter is reduced, the balls are collected at the center of the ball vibrating container in the ball adsorption step (step 7 of the second embodiment) to form a cluster. To do.

When the ball diameter is 250 μm or less, the weight of the ball is light, so that the ball gathers at the center of the ball suction head during the suction of the ball and forms a cluster as time passes. Further, when the diameter of the ball is about 100 μm, the ball gathers at the central portion, and the time for forming a cluster becomes very fast. A cluster is a state in which balls are gathered, and has various shapes. Since the balls are supplied in such a manner that one layer is provided on the bottom surface of the ball vibrating container and covers 50% of the balls, when the balls are collected at the center, the balls are not supplied to the suction holes in the peripheral portion of the ball suction head.

When the suction of the ball is started, the ball suction head 5 sucks air, so that the ball rides on the air flow in the ball vibrating container 20 and gathers at the center of the ball suction head 5. After a predetermined time from the start of the suction, the ball suction head 5 is moved upward to temporarily stop the ball suction operation.

When the ball suction head 5 moves upward, the balls gathered at the center are not affected by the air flow from the ball suction head 5, so that the force to move to the center does not work and the ball vibration container vibrates. The set or cluster of balls gathered at the center is broken, and the balls spread over the entire surface of the ball vibrating container in 1 to 2 seconds.

Thereafter, the ball adsorption is performed again. It is also included in the present invention that such a ball suction operation is temporarily stopped a plurality of times.

Generation of clusters can also be prevented by improving the apparatus.
The ball suction head 5 is hollow so that the balls can be vacuum-sucked by all the suction holes. A plate or net (hereinafter referred to as air resistance) that causes air resistance in the hollow ball mounting head 5 so that the amount of air passing through the suction hole in the center of the ball suction head is smaller than the air passing through the suction hole in the peripheral part. , An air resistance member) is provided so that the balls do not collect at the center of the ball suction head 5 during the suction.

The shape of the air resistance member is circular, elliptical or square depending on the shape of the ball mounting head. The mounting position of the air resistance member is a central region excluding the peripheral portion of the surface where the suction holes are provided in the hollow portion in the ball suction head. With respect to the cross section of the hollow portion of the ball suction head 5, ball center formation can be prevented by making the central region of the head smaller than the peripheral portion of the head and increasing the air resistance of the central region. The air resistance member is made of transparent plastic or glass so as not to block incident light from the ball adsorption inspection illumination 7.

In the present invention, the balls include solder balls, metal balls, ceramic balls, plastic balls, and composite balls thereof. The flux includes a paste containing rosin, a solder paste containing a minute solder, a conductive adhesive, and the like. The drive device is a servo motor, a step motor or a linear motor. Moreover, although the circuit board was illustrated as the board | substrate 15, a semiconductor wafer is also included. In the case of a semiconductor wafer, the land 44 becomes an external electrode terminal of the semiconductor element. The land 44 of the present invention refers to a connection terminal for circuit wiring.

Further, in the present invention, in order to prevent the flux from scooping up due to the surface tension above the transfer pin 25, it is preferable that the intermediate portion has a larger contact angle with the flux. Specifically, the intermediate part is covered with a fluororesin or the surface of stainless steel is exposed.

In the present invention, heating of the cleaning surface 40 is exemplified, but heating of the transfer pin 25 or heating of the flux on the flux table 32 also adjusts the viscosity of the flux belongs to the present invention.

The ball mounting method of the present invention includes a plurality of steps, but the order is not limited to the embodiment. For example, it is clear that the case where the flux transfer process is after the ball adsorption process does not depart from the spirit of the present invention.

  The flux cleaning device and the cleaning method according to the present invention can be used for cleaning in a flux transfer operation for soldering and an adhesive application operation, in addition to the ball mounting device and the ball mounting method.

  Furthermore, it can be used for a method that requires precise adjustment of the transfer amount by adjusting the temperature of the flux or adhesive.

It is a plane arrangement view of a ball mounting device. It is front sectional drawing of a transfer head. It is AA sectional drawing of FIG. It is a top view of a transfer unit. It is AA sectional drawing of FIG. It is a top view of a cleaning unit. It is AA sectional drawing of FIG. It is a top view of a board | substrate. It is a top view of a chip substrate. It is a figure which shows typically 1 process of repair operation. It is a flowchart of a ball mounting method. It is a flowchart of the method of cleaning a flux.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Loader, 2 ... Transfer head, 3 ... Transfer unit, 4 ... Cleaning unit, 5 ... Ball adsorption head, 6 ... Ball supply unit, 7 ... Illuminating device, DESCRIPTION OF SYMBOLS 8 ... Ball mounting inspection apparatus, 9 ... Unloader, 10 ... Repair unit, 11 ... Board guide, 12 ... Y-axis slider, 13 ... X-axis slider, 14 ... Slider , 15, 15a, 15b ... substrate, 16 ... CCD camera, 17, 17a, 17b ... squeegee, 18 ... slider, 19 ... parts feeder, 20 ... ball vibrating container, 21 ... Ball amount detection sensor, 22 ... Pin unit, 23 ... Pin guide plate, 24 ... Fixing member, 25 ... Transfer pin, 26 ... Pin holding plate, 27 ... Pin Unit fixing plate, 28... 29, 30 ... Air vent hole, 31 ... Squeegee guide, 32 ... Flux table, 33 ... Flux, 34 ... Connecting member, 35 ... Drive device, 36 ... Ball screw 37 ... Barriers, 38 ... Cleaning table, 39 ... Heater, 40 ... Cleaning surface, 41 ... Insulating material, 42 ... Chip substrate, 43 ... Cutting line, 44. ..Land, 45 ... ball, 46 ... repair head, 47 ... suction hole

Claims (2)

Becomes the transfer device and the ball to be transferred to the substrate flux in the transfer pin and a mounting device to be mounted on the substrate, the above transfer device consists of a transfer unit and a cleaning unit and the transfer head, the mounting device ball suction head and the ball In the ball mounting device consisting of the supply unit,
The cleaning unit includes a cleaning table, a heater, and a heat insulating material.
The cleaning table has a cleaning surface for transferring the flux adhering to the transfer pin on the upper surface thereof,
The heater for heating the cleaning surface is set in a hole processed in the cleaning table,
The ball mounting apparatus, wherein the heat insulating material is disposed below the heater so that heat from the heater is not transmitted downward . A ball mounting method for mounting a ball on a land of a substrate onto which a flux is transferred with a transfer pin, the step of attaching the flux to the transfer pin disposed on the lower surface of a transfer head; and the flux on the land Applying from the transfer pin, cleaning step for cleaning the flux adhering to the transfer pin, adsorbing the ball on a ball adsorbing head, and mounting the ball on the land In the ball mounting method consisting of
In the cleaning step, the transfer head is moved onto a cleaning surface heated by a heater set in a hole processed in a cleaning table, the transfer pin is brought into contact with the cleaning surface, and attached to the transfer pin. A method of mounting a ball, wherein the transfer head is raised after the flux being transferred is transferred to the cleaning surface .